This invention relates generally to the field of 35 mm motion picture photography, and more particularly to a method and apparatus for adapting a 35 mm single lens reflex (SLR) still camera to function as a 35 mm motion picture viewfinder able to record images, which include 35 mm motion picture format markings.
In the process of motion picture production and especially during pre-production, it has always been useful to anticipate both the creative impact and the practical requirements of proposed scenes. As scenes are built from individual shots and shots are the result of camera placement and lens choice it has been found to be even more useful and revealing to preview individual shots as they will be captured by the motion picture camera. The tool used for preview of this sort is called a viewfinder, sometimes referred to as a director""s viewfinder. The most accurate and realistic viewfinder would be the actual viewing system of the intended motion picture camera itself. An image formed with this equipment would present to the viewer all of the qualities and characteristics of the image eventually recorded on film. However, these cameras are cumbersome and extremely expensive as are the lenses used with them. For this purpose, substitutes for the motion picture camera have been developed.
A shot is the image formed by a chosen lens placed in a particular location focused on a chosen subject and set at a determined aperture. The basic optical characteristics of an individual shot are field of view, perspective, and depth of field. The most useful viewfinder will represent all of these characteristics. To this end, one form of viewfinder eliminates the motion picture camera and substitutes a simple viewer on which motion picture lenses can be mounted. This is an excellent substitute reducing some of the bulk of equipment, but it requires the use of motion picture lenses and therefore has similar limitations including size, weight, and expense. Smaller, lighter viewfinders have been created, which, through telescoping optics and a physical masking mechanism, define the area which would be included in individual motion picture formats. Although these viewfinders approximate the angle of view of a particular focal length lens given a particular format, they do not represent any other optical qualities of that lens.
Video systems, which electronically mask or mark the aspect ratios of motion picture formats on images they gather have been created, but their optical systems form images on their recording medium of a different size than motion picture photography. Therefore, there is no correspondence between lenses used with this type of viewfinder and lenses used later during motion picture production. The optical characteristics of the lenses in this view-finding system are not representative of those used in motion picture photography. Finally, a viewfinder can be made from two reticles, which define a field of view when properly aligned. This viewfinder is very light weight and inexpensive, but it can reveal no more than field of view.
Previous viewfinders suffer in varying degrees from one or more of the following limitations: expense, inconvenience, or inaccuracy. To present an accurate and realistic representation of the image, the viewfinder must form the image in its actual size. If the size of the image formed in the viewfinder is the same as it will be when formed in the motion picture camera then all other optical characteristics will be comparable. A lens of a particular focal length will present the same angle of view when fitted to the viewfinder or to a motion picture camera, and the qualities of perspective and depth of field will also be identical.
Furthermore, none of the viewfinders mentioned above are capable of creating photographs, which are an accurate record of what is seen through them. Some systems have been equipped with video or digital still recording devices. In one system, a video record of the image formed on a focusing screen within the viewfinder is made by a secondary optical system. These indirect means limit the accuracy of the system particularly as it relates to depth of field and perspective. In another system, the video image is recorded directly, but the image size is not the same as a motion picture camera""s and therefore the optical qualities of the image are different (because the focal length of the lens is different) although the angle of view may be the same.
In the past, camera manufacturers have offered replacement focusing screens with markings, which corresponded to the 1:1.33 television aspect ratio. These markings were a useful aid when composing a still photograph to be presented in the television format. In designing these markings, no consideration was given to the actual dimensions of television or motion picture photographic image areas. Therefore, the markings did not imply a direct reference regarding equivalent focal length in television or motion picture photography.
A primary advantage of the invention is to provide a method and apparatus for adapting a 35 mm SLR still camera to function as a 35 mm motion picture viewfinder.
Another object of the invention is to provide a method and apparatus for adapting a 35 mm SLR still camera to record motion picture format markings on photographs exposed in the camera.
Another object of the invention is when fitted with a lens of a specific focal length a 35 mm SLR still camera reveals the area photographed by a 35 mm motion picture camera fitted with a lens of the focal length.
Another object of the invention is when fitted with a lens of a specific focal length a 35 mm SLR still camera may record motion picture format markings on photographs exposed in said camera revealing the area photographed by a 35 mm motion picture camera fitted with a lens of the focal length.
A further object of the invention is to provide a more accurate and realistic motion picture viewfinder, which through the use of interchangeable or zoom lenses reveals all optical characteristics of a lens of a given focal length and aperture including depth of field, perspective and angle of view.
In accordance with a preferred embodiment of the present invention, an apparatus for adapting a 35 mm SLR still camera to function as a 35 mm motion picture viewfinder comprises a replacement focusing screen for a 35 mm SLR still camera accurately scribed with 35 mm motion picture format markings and an insert placed in front of film accurately scribed with 35 mm motion picture format markings.
In accordance with another embodiment of the invention, a method for precisely coordinating markings seen on the focusing screen of a 35 mm SLR still camera through its viewfinder with markings transferred to photographs exposed in said camera comprises the steps of marking a replacement focusing screen and an insert installed against the film aperture plate between film guide rails with accurate markings of 35 mm motion picture formats.
Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.